1. Field of the Invention
This invention relates to apparatus useful for quickly connecting and disconnecting tools and stem sections in a wireline tool string.
2. Description of the Prior Art
Wireline equipment is frequently used to install and retrieve well tools through a flow conductor disposed in a well bore. In the past, wireline tool strings have been assembled from components have traditional "sucker-rod" threads. Making and breaking such threaded connections has previously required the use of pipe wrenches. Workers have often sustained injuries from slipping wrenches and from burrs caused by the use of such wrenches. The use of such wrenches has also increased the wear and tear on tools. Improperly threaded connections and stripped threads have also contributed to back-offs and other downhole failures, necessitating fishing trips with their associated downtime and expense.
In an effort to overcome problems previously encountered with threaded connections, coupling devices have been produced that utilize a bayonet-type connection in which a pin end comprising locking lugs is inserted into a box end comprising annular recesses adapted to receive the locking lugs. When the pin end is rotated relative to the box end, the locking lugs engage shoulders that limit further axial movement therebetween; Spring-biased locking members have also been disclosed for use in restricting further rotational movement between the pin and box ends once they are fully engaged and the locking lugs are rotated into the locking position within the annular recesses. However, other difficulties have been encountered with these connectors.
Some of the conventional, commercially available connectors undesirably require the use of a special wrench, key, or other tool for releasing the pin and box ends during disassembly.
Others, particularly those having axially spaced sets of locking lugs on the pin end, are susceptible to being rotated before the pin end has been fully inserted into the box end during assembly. This causes delay in realigning, fully inserting, rotating and locking the pin end in the box end.
Unintended hang-up can similarly occur during disassembly if the pin end is rotated slightly during withdrawal, causing one set of locking lugs to undesirably engage the wrong annular recess. This also necessitates realignment before the pin and box ends of the connector assembly can be axially disengaged.
Finally, difficulties have been encountered because conventional quick-lock connector assemblies lack external indicia that enable users to determine relative rotational alignment between the pin and box ends at a glance.
A manually operable connector assembly for use with wireline tool strings is therefore needed that does not require the use of wrenches or other special tools, that comprises pin and box ends which cannot be unintentionally rotated into hang-up during assembly or disassembly, and that comprises external indicia which enable users to determine relative rotational alignment between the pin and box ends.